Ag ultramicrotome

These experiments were done at Electron Microscope Unit of Assiut University. Specimens of PBW 10 day's old larvae of (for both treated and untreated check) were killed by chloroform, and fixed in aqueous neutral buffer. A block of 1 x 2 mm was taken from each sample at the level of the 4 th abdominal segment, and kept in 5 % cold glutaraldehyde directly after dissecting for 24 -48 hr. Samples ware then rinsing in cacodylate buffer (pH 7.2) 3 -4 times for 20 min every time and post fixed in 1 % osmic acid for 2 hr, then washed again 4 times as above. Dehydration by subsequent ascending levels of alcohol (30, 50, 70, 90 and 100% for 2 hr) of each specimen was done. The specimens were implanted epomaraldite mixture as said by (Bozzol and Russell, 1991) . From the implanted sectors semi thin sections by L K B extremist -microtome in thickness of 0.5 μm were formed to be photographed by using sc30 Olympus camera, ultrathin section in thickness of 500 -700 A were created using Leica AG ultra-microtome and distinguished in uranyl acetate and lead citrate, as required. The sections were inspected by JEM 100 CXII electron microscope at 80 Kv and photographed by CCD digital camera Model XR-41.